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Setting up a metal mold - CNC


#1

I have a question for any of you CNC guys out there - Just how do you
set up a two part metal mold to ensure proper alignment when
injecting the pattern material? I have my own method, which seems a
bit hit-and-miss, so I would like to hear from someone doing this on
a regular basis.

A direct off list response might be best since this topic may
involve some back and forth emails which may be of no interest to the
majority of Orchid subscribers.

Thanks, Aufin01@comcast.net


#2

Aloha, Long time no hear. You need to set up a pin or dowel pin
master for the mold and subtract the model. If you need help or want
to do it on list to help others its ok with me. I know you are using
ArtCAM so, I can help. But others using other 3D design software, may
also benefit. If you want contact me of list, thats ok too.

Best regards, Christian Christian Grunewald Precision Modelmaking
Technologies Hawaii (808) 622-9005 Christian@3Dclipart.net
ChristianG@WylandGalleries.com


#3

Dear Aufin & All Here’s some nice and juicy stuff for all the Orchid
Police! Even though I have been doing this since 1978 I’m sure
someone will say I’m all full of it!

Metal molds for jewelry production (in my region) have been around
since the 50’s and 60’s. At that time the whole mold was made of a
lead like material that melts like candle wax. I started making metal
molds in 1978. The basic process has changed little.

Class rings-

With metal molds for class rings you need to start out with a metal
model mounted on a metal arbor that is the finger size. If you align
this master proper you only need one good side. Each mold half is
made from this one good master side. You put two sides together to
make one mold. This lead like material is poured into a press-like
devise and squished to capture all the detail of the master. With
some molds it is also heated so the material flows around the master.
Alignment is done when fixturing the model into the molding frame.
This is one of several hard parts. There are no commercially
available fixturing frames. You must make your own. Each
manufacturer may end up spending a fortune on their own sets
fixturing frames. That is why many class rings are the same style. If
the style varies greatly and requires new or different holding
fixtures you end up spending a fortune. The process also requires
fixtures at different functions that all hold the mold uniformly. For
example after the molds are initially poured the need to be surfaced
so each side is flat to the other side. The side is digitized into a
CAD system. This surface is then imported into a surfacing CAD
program and given surface relief. After a tool path is generated for
the CNC mill, the detail is cut into the mold half. Great precision
is possible. Both tooled sides are assembled and clamped together
with a different arbor for wax injecting. This is where additional
alignment is accomplished. Injection may be as much as 100 psi of wax
pressure depending on the wax injector.

Regular jewelry-

Metal mold can make many different styles of jewelry. Typically it
is for thin waxes and possibly plastic injection. These mold are all
poured in various stages with one layer or level being done before
another is worked on. That is how many hollow wax rings are made,
from metal molds. The wall thickness is also consistent because you
are many times tooling the mold and not the wax.

Current jewelry-

One of the current methods of mold making consist of using plastic
and silicone. To see a demo go to: www.ajt-online.com. The cost on
traditional metal mold is outrageous. Not only that, trying to find
someone to make them is also difficult.

Best Regards,
Todd Hawkinson